It has since the radio and television techniques first were developed, been popular to record both music and other transmissions over radio and television. Examples of this could be songs, films and music events. Recordings are made both to be able to save and repeatedly enjoy a particular appreciated transmission, as well as to not have to be restricted to listen/view only at the time of transmission. One problem with recording, e.g., music from radio transmissions, is that the listener in most cases does not know which song will be transmitted. In many cases, the song has already been played for a while before it is possible to recognize that it is a song that should have been recorded from the beginning. In addition to this, it is time-consuming to pay attention to the radio for a certain song or watch for a certain film if the transmission time is unknown.
As prices of music and film on CD, DVD and other storage media increase, new less expensive alternative ways of making such entertainment available have been developed. The Internet has now a bigger role in a more or less legal or illegal spreading of music in different file formats. In particular, music and film are copied and made available for the general public over the Internet in, for instance, MP3 format. The interest for free music is shown, for instance, by the large number of users of home pages with search engines that give them availability of free music; an example of this is Napster.com.
It is also interesting to note that a great proportion of the persons who listen to music has limited knowledge of which artists they are listening to and only listens to radio stations with mixed, for them not always known, artists. That the consumer is more interested in music from a certain genre than in specific artists is also shown in an increasing interest in music CD's with mixed groups/artists.
The patent application DE 19810114 describes a method of searching and matching previously stored parts of music, called keys, against transmitted music over chosen radio channels for automatic recording of a chosen song when these keys match the transmitted song. For each song that is to be searched for and recorded, a start key in the form of a part of the beginning of the song and an end key in the form of an end-piece of the song, is stored in a memory in the radio. Those in advanced chosen keys are compared against everything that is transmitted over a number of radio channels and when a key is found, the part in-between is recorded. It is also possible to search for a certain type of music by storing category keys for matching and recording of a specific music category such as pop music, rock music, classical music or other type of music.
One disadvantage of this way of recording music is that only previously chosen music in the form of parts called keys of music previously stored on, e.g., a CD can be matched against radio channels for recording of wanted music. It is not possible to extract one or more keys from any song that is played on the radio for continuous matching against radio channels, enabling one to automatically get a full-length version of that song. Another disadvantage is that it is not possible to record music completely without undesirable signal components since everything between the keys is recorded, which will mean that undesirable signal components such as talk and distortion due to bad transmission will be included in the songs. It is common that radio talkers or commercials interrupt the music in radio transmissions.
The present invention is meant to solve the above mentioned problems by supplying a procedure and a device for the searching and recording of desired source material in media channels containing undesirable signal components, where the same source material is transmitted at least twice, either in the same channel or in different channels. A piece of source material can be a song, a film or anything else that is time-limited and can be considered as separate from other material. More particularly, if needed, the signals are continuously buffered in memory in a receiving member, over at least one media channel. The next step may involve identifying and choosing a desired source material by an activation member connected to the receiving member. Out of this desired source material, a section or a representation of the section may be taken as a search key. The device may also select search keys automatically in one version of performing the invention. The media signal located around the search key may then be stored in a memory. The search key is compared to other stored media signals or current transmissions of media signals. If a second instance of the search key is detected, signal sections that in time are connected to the search keys are compared. The signal sequences that by comparison have been found to be substantially identical are identified as belonging to the same source material. Identifying common segments between the first signal segment and the second signal segment enables one to find the beginning and end of the commonality, and thus the beginning and end of the whole or part of the source material. These common segments may be stored for later use.
The next step may be an iteration of the above mentioned detecting of search key, storage in memory and comparison among media signals where signal segments that are identified as originating from the same source material can complement the earlier found common segment. This can result in a longer, more complete and higher quality segment of source material than could be gotten initially.
The iteration may be terminated by a threshold value for termination and whereby an acceptably long common segment of sufficient quality has been identified and stored in the final memory place for playing later on.
The invention gives the user unique new ways of continuously obtaining recordings of source material, such as music and film. If this invention is used for radio transmissions, the invention can continuously record all songs repeated on the radio and save them in a play list for later use. In addition to this, when the user of the device hears a song he wants to record, the user only has to push a button to automatically get a full-length recording of that song. The invention may distinguish between music, commercials and talk on the radio.